Open Port Vulnerabilities Are Silent Threats. Here’s What You Should Know About Them.

In July 2021, North Carolina’s Sunset Beach was the target of a series of ransomware attacks for six weeks. The ransomware was able to penetrate their systems through an unused port. The only documents that were lost in the incident were those that were stored on desktops and not from town servers. Fortunately, almost all the lost files were recovered by the town’s IT department. 

The following incident is an example of the potential threat of open ports. While this attack was handled efficiently, it could’ve been avoided. 

Here, we will discuss open ports, port scanning and how it can be exploited, common open port vulnerabilities, and how to manage ports efficiently to protect your organization.   

What are open ports?

Physically, ports refer to an opening on a device that allows it to connect to other hardware and perform a service – for example, HDMI cables, ethernet ports, headphone jacks, etc. Network-wise, ports are virtual gateways that facilitate communication and transmit data over the internet between different devices and operating systems. The two kinds of ports used are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). 

Ports are essential to execute basic services like browsing the web, sending emails, or transferring files over the internet. Each port is assigned a number and cannot run any other service than the one it is designated for.  

There are 3 different types of port states:

• Open ports: Here, a port is configured to accept packets of data and run a service.
• Filtered ports: The establishment of a firewall regulates all traffic within a network, allowing only certain approved data packets to be accepted. 
• Closed ports: When all connections or packets are rejected by a port, it is considered to be closed.

Some of the most commonly used ports are:

• Ports 20,21 – FTP (File Transfer Protocol)
• Port 22 – SSH Remote Control Login
• Port 53 – DNS (Domain Name Server)
• Port 110 – POP3 (Post Office Protocol)
• Port 80 – HTTP (Hypertext Transfer Protocol)
• Port 25 – SMTP (Simple Mail Transfer Protocol)

Usually, administrators only open ports that are required. However, some ports may be opened by default or to facilitate the operation of the main port. While open ports aren’t inherently a security risk, they can become targets for cyberattacks, who can use vulnerabilities to access sensitive information or launch larger cyberattacks.

What is port scanning?

Port scanning is the process of scanning computer ports – pretty straightforward. This procedure allows system administrators to identify open ports, find out if they are running services, and gather information from the servers to which the ports are connected. It is also used to determine whether a network is affected by any security vulnerabilities. This process is an important element of cybersecurity maintenance, especially in large organizations, where it is cumbersome to constantly monitor all device ports in a network.

TCP SYN Scan, TCP FIN Scan, and Ping Scan are some of the common methods of port scanning.

While port scanning is an essential process to reduce risks, it can also be utilized by cybercriminals looking to find potential open port vulnerabilities to exploit. Once a port scan reveals accessible open ports, threat actors can fingerprint all services running on a device, the protocols that are in function, the information about the programs and software it runs to determine if there are any vulnerabilities that can be used to their advantage.

Common threats that can occur due to open port vulnerabilities

Open ports enable communication and the exchange of information between different devices within a network. Malware can be easily spread through this line of contact to run malicious services in order to compromise the network. The set of common ports which are used to spread malware are referred to as Trojan ports.

Open ports that are not guarded properly provide threat actors the opportunity to run a port scan and discover all publically accessible ports within a network. They can then target services running on the ports with DoS (Denial-of-Services) attacks and overwhelm them, ultimately shutting them down.

Vulnerable and misconfigured services running on open ports can often become targets of breach attacks. Threat actors can exploit these vulnerabilities, gain unauthorized access to a network, and steal sensitive data or credentials, which can be used to launch brute force attacks.

How to mitigate open port vulnerabilities

Most organizations heavily utilize open ports and the array of services running on them, which is why you should take the necessary steps to ensure maximum security.

1. Implement strong firewalls that will filter incoming and outgoing traffic and only accept trusted data packets. Additionally, install security controls like antivirus, antimalware, encryption, and multi-factor authentication to ensure that all system devices are secure from security breaches.

2. Regularly update all applications and services utilized in your organization to the latest requirements to eliminate any vulnerabilities that cyber attackers could use to their advantage. Employ endpoint security programs and solutions to ensure added security on all system devices.
   
3. Limit open ports to only essential ones or to those that are currently in use to reduce security risks.
   
4. Regularly monitor your network’s open ports and the applications running on them for any vulnerabilities, suspicious activities, or oddly high levels of network traffic.